Tense, aspect and mood are all features of verbs, which are words used to describe actions or states of being. Plato defined verbs as denoting action whereas Aristotle described them as having “a composite sound with a meaning, indicative of time” (Binnick, 1991: 3). Thus, tense is the foremost feature of verbs. There are also other features such as number, person, and voice, but attention in this study is given to tense, as well as aspect and mood.
Traditional English grammar in general derives from classical Greek and Latin. Within this framework, each word is assigned to one of usually eight parts of speech, and numerous rules are learned for composing sentences. This was a popular approach for learning the language until fairly recently because its effectiveness has been questioned. Modern theories have shown many deficiencies of the traditional grammar approach, which is typically complex and highly prescriptive. In practice, "There are matters of style, matters of change (albeit extremely slow change) and matters of dialect" (Bauer, 2007). Furthermore, substitution frames for example, do not always help, and they can become cumbersome for structuralists to define for all instances of word occurrences. Moreover, differences between form and function can arise.
Descriptive grammarians on the other hand attempt to describe the language as well as explain why it is the way it is, and various theoretical models are used for the purpose. In this regard, Chomskys work on transformational generative grammar was very significant in shaping modern linguistic theories. The modern discipline of generative linguistics made its appearance from the 1960s.
However, as many linguists have experienced, modelling verb systems of many languages is a very complex affair. Bache et al., (1994) view the semantic complexity of language-specific categories as “the main problem in the analysis of any verb system”